I think the old Sun Super Tach was the most popular back then. They aren't made any more but this one is a spittin' image of the original. Bosch Retro Line Tachometer Gauges FST8000
I think Sun were lately made by Sunpro. Here's a little info from Summit:
Sunpro began manufacturing industrial tachometers for Jeeps and tanks in 1935 and evolved into one of hot rodding’s most well-known suppliers of tachs and gauges. The iconic Sun Super Tach could be found inside cars at dragstrips across the country during the 1960s and quickly became one of the most popular tachometers by 1970. Sunpro has since expanded its product line to include a variety of gauge styles and became the first company to offer its tachs and gauges with color dial faces, lighted pointers, and chrome bezels. You’ll find a huge selection of Sunpro tachometers, gauges, and gauge installation accessories at Summit Racing—shop now!
As an owner of a brand new Dodge Dart Sport 340 back in 1973, that tach in the above pick looks like the exact tach that I installed in it....in just about the same spot too.